<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes" />
    <title>ShellCheck: SC2175 – Quote this invalid brace expansion since it should be passed literally to eval</title>
    <link rel="stylesheet" href="css/bootstrap.min.css" />
  </head>
  <body style="margin-left: auto; margin-right: auto; max-width: 800px">
    <h1>SC2175 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC2175">See this page on GitHub</a>
    <p style="display: none"><a href="index.html">Sitemap</a></p>
    <hr />
    <h2
id="quote-this-invalid-brace-expansion-since-it-should-be-passed-literally-to-eval">Quote
this invalid brace expansion since it should be passed literally to
eval</h2>
<h3 id="problematic-code">Problematic code:</h3>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC2175.html#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="bu">eval</span> echo {1..<span class="va">$n</span>}</span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC2175.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="bu">eval</span> <span class="st">&quot;echo {1..</span><span class="va">$n</span><span class="st">}&quot;</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p>Using <code>eval somecommand {1..$n}</code> depends both on bash
silently failing to interpret the brace expansion, and on it passing
failing brace expansions literally.</p>
<p>Rather than depending on these questionable features (which already
behave differently in other shells), use the explicit, predictable way
of passing values literally: quoting.</p>
<h3 id="exceptions">Exceptions:</h3>
<p>None.</p>
    <hr />
    <p style='font-size: 80%'><a href="../index.html">ShellCheck</a> is a static analysis tool for shell scripts. This page is part of its documentation.</p>
  </body>
</html>


